Donald Sterling had until midnight Eastern time on Tuesday to respond to the charges levied by the league, which has already banned him for life and fined him $2.5 million over racially charged remarks that became public in April.

The NBA has already set a June 3 hearing at which owners could strip the team from Sterling, but US media reports on Tuesday seemed to indicate that Shelly Sterling might be trying to negotiate a sale by then.

Gossip website TMZ.com and sports network ESPN were among the media outlets reporting that Shelly Sterling has fielded inquiries from at least six serious bidders for the club that could fetch up to $1 billion.

Steve Ballmer, the billionaire former chief executive of Microsoft, has been mentioned as a front-runner among potential buyers.

Other suitors reportedly include Patrick Soon-Shiong, a surgeon, professor and billionaire businessman, NBA Hall of Famer Magic Johnson, former NBA player Grant Hill and his own group of investors, music mogul David Geffen and Oracle chief executive Larry Ellison.

Donald Sterling surrendered control of the Clippers last week to Shelly Sterling, who was a part-owner of the team but wasn't banned by NBA Commissioner Adam Silver when he sanctioned her husband.

However, the NBA said that it would proceed with its efforts to strip Sterling of the club, and league officials say that if that goes through Shelly Sterling's ownership stake would be terminated along with her husband's under terms of the franchise agreement Donald Sterling signed when he bought the club for $12 million in 1981.

TMZ reported that Shelly Sterling and her lawyer Pierce O'Donnell have told potential buyers they are looking to make a deal this week, and that Silver is aware of their intentions.

Any new owner must be approved by other league owners, and not just win a bidding war for the Clippers.

The mess began in April, when TMZ posted a recording of Donald Sterling saying he did not want his girlfriend bringing black people to Clippers games or posting photos on social media of herself with black people.

Sterling later apologized, said he had made a "terrible mistake" and the 80-year-old real estate tycoon claimed he was goaded into making the comments as he was trying to seduce the woman, known only as V. Stiviano.